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Postpartum anoestrus in five seasonally‐calving dairy farms in Victoria, Australia
Author(s) -
Plozza KL,
Beggs DS,
Mansell PD,
Stevenson MA,
Blackwood CB,
Pyman MF
Publication year - 2016
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/avj.12465
Subject(s) - ice calving , herd , zoology , odds ratio , confidence interval , odds , logistic regression , medicine , pregnancy , biology , lactation , genetics
Objective A cross‐sectional study of seasonally‐calving dairy cows in south‐western Victoria to quantify the prevalence of anoestrus and to assess the effect of body condition score ( BCS ), days in milk ( DIM ) at mating start date ( MSD ) and age on the likelihood of being diagnosed as anoestrus. Methods Age, DIM and BCS details were collected from 1795 cycling and 1399 cows diagnosed as anoestrus in five seasonally‐calving dairy herds in Victoria. Multivariable logistic regression was used to quantify the association between BCS , DIM and age and the probability of being diagnosed as anoestrus. Results The apparent prevalence of anoestrus in cows that took part in the study was 44% (95% confidence interval ( CI ) 42–46%). The risk of anoestrus increased with decreases in DIM and BCS . There was a significant interaction between BCS and DIM . For cows >90 DIM at MSD (the reference category) the odds of anoestrus in cows with BCS <4.00 was 8.05‐fold (95% CI 3.2–20.2) that of cows of BCS ≥4.50. The risk of anoestrus decreased with increases in cow age. Cows aged 2 and 3–5 years had 2.4‐fold (95% CI 1.79–3.22) and 1.4 (95% CI 1.11–1.77) odds of anoestrus, respectively, compared with cows aged ≥6 years. Conclusion Reproductive management to maximise the number of days calved at MSD and nutritional management to ensure cows are in BCS >4.5 at mating will reduce the prevalence of anoestrus in Victorian dairy herds.